This invention relates generally to a fluorescent lighting fixture and, in particular, to a replacement lighting adaptor for adapting a fluorescent lamp to an incandescent lamp connector.
Compact fluorescent lamps are widely used as an energy efficient substitute for conventional incandescent lamps. A four-tube compact fluorescent lamp, commonly referred to as a "quad-lamp," is capable of producing, with between 9 watts and 13 watts, the equivalent lumens of an incandescent lamp of much higher wattage. In order to provide replacements for incandescent spotlights and floodlights, it is known to package a compact fluorescent lamp with its required magnetic ballast within a housing having a reflective surface and covered by a lens. One application for such replacement of a fluorescent lighting device is within a housing recessed within a ceiling. Another application is engagement with a surface-mounted incandescent lamp holder.
A problem with such replacement fluorescent lighting adaptors is meeting the dimensional constraints imposed by the incandescent lamp holders and fixtures to which they are applied. One such dimensional constraint is the maximum overall length, or MOL, of the replacement fluorescent lighting adaptor. The acceptable MOL is strictly limited by the dimensional constraints of existing fixtures, such as recessed ceiling lights. In order to reduce MOL, it is well known to position the magnetic ballast around the contact portion of the fluorescent lamp. The problem with this approach is that, in order to utilize such a design to reduce MOL, it is necessary to enlarge the diameter of the replacement fluorescent lighting adaptor housing adjacent the threaded Edison contact assembly which is the portion which threadably engages conventional incandescent light sockets. This increase in diameter may preclude the use of such a replacement fluorescent lighting adaptor in conventional surface-mounted incandescent spotlight and floodlight housings. Such housings typically have a narrow portion adjacent the threaded contacts or Edison base.
An additional demand placed upon the design of replacement fluorescent lighting adaptors is the desire to provide a power-factor correcting device, namely a capacitive device, in the lighting adaptor housing in order to correct a lagging power factor created by the magnetic ballast. In order to be effective, such capacitor must be of sufficient capacity and be capable of operation at high voltage AC. Such capacitors tend to be of significant size. Another consideration in the design of replacement fluorescent lighting adaptors is the undesirable effect of heat generated by the magnetic ballast upon the efficient operation of the fluorescent lamp. Such fluorescent lamps are less efficient and produce less light output at elevated temperatures.